European Rotors - Certification by Simulation

HELICO PTERS DIVISIO N
Certification by Simulation: Leonardo Helicopters’ view and
experience
Colonia, November 18th, 2021
Andrea Ragazzi
Leonardo Helicopters Division, Flight Mechanics

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© 2019 Leonardo - Società per azioni 2
• Leonardo Helicopters’ experience in certification by simulation.
• What’s next? The RoCS (Rotorcraft Certification by Simulation) project.
• Leonardo Helicopters’ view on certification by simulation.
Summary

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© 2019 Leonardo - Società per azioni
Leonardo Helicopters’view on certification by simulation:
what rules say
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A flight demonstration would be too risky even
after attempts are taken to mitigate these
risks (e.g., by mock takeoffs/landings in the
air at a safe altitude);
Required environmental condition are too
difficult to attain (…).
Whenever repeatability is required, or
demonstration of a specific scenario with a
range of pilots.
Simulation may be an acceptable alternative to flight
demonstrations in certain situations, such as:
FAA AC25-7D
Flight Test Guide for Certification of Transport
Category Airplanes
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the advantagetriangle
Costs
Safety
Effectiveness
Increase in safety due to the
possibility to demonstrate
by simulationflight
conditions that could be
risky.
Possibility to test different
configurations/conditions to
enhance insightwith limited
increase in cost and time.
Reductionof costs
associated with flight
testing.
Riccardo Bianco Mengotti,
The Advantages of Virtual Engineering in the
Rotorcraft Flight Mechanics Design Process,
Rotorcraft Virtual Engineering Conference,
Liverpool 2016

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Reach a level where the users can say “I believe
the simulation is credible and I am comfortable
taking the needed decision with it”.
Simulation model credibility
what literature says
W. Oberkampf, C. Roy, Verification and Validation in
Scientific Computing, Cambridge University Press 2010

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Simulators are already accepted for rotorcraft
training. Modeling metrics, and cueing standards
are defined to ensure that these devices are “fit-
for-purpose” by CS-FSTD(H).
the simulation in training vs. the simulation for certification
The purpose of a certification simulator is
different and these special needs must be
considered in the development of the simulation
approach for certification.

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simulation models able to predict the
physical behaviour of the rotorcraft
with ‘sufficient’ accuracy for the task in
hand;
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To be effective, simulation requires:
simulation for certification quality level
in the case of pilot-in-the-loop
simulations, hardware able to provide
adequate cues to the pilot (visual cues,
motion cues, aural cues).

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Leonardo Helicopters target is
to cut down certification flights
by half in 10 years.
roadmap

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Summary

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AW189 Engine-Off-LandingCertification by Simulation:background and
Motivation
The civil certification basis (CS29) requires demonstration of the engine-off-landing capability of
the rotorcraft (requirements: CS 29.75(b)/CS 29.79(b): landing, CS 29.143(a)(2)(vi):
controllability-manoeuvrability).
EOL is a complex emergency manoeuvre.
EOL phases are:
1. Entry in autorotation.
2. Steady autorotation.
3. Deceleration (flare).
4. Descent arrest.
5. Touch-Down.

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The Previous experience
• Partial manoeuvre is possible in flight with engines on but is not representative of the full
manoeuvre.
• A real touchdown can be required for certification (FAA on AB139, 2004).
• A real touchdown always implies some risk.
AW189 Engine-Off-LandingCertification by Simulation:Backgroundand
Motivation

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The AW189 rotorcraft
• Oil & Gas, SAR, Corporate, VIP, Law Enforcement and Homeland Security
• Flexible and comfortable passenger cabin, with up to 19 crashworthy seats
• Single pilot day/night VFR/IFR
Twin engine “Super-Medium” 8+ tonnes class helicopter

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AW189 Engine-Off-LandingCertification by Simulation:
The AWARE SimulationApproach
What was needed to achieve the objective:
• The mathematical model.
• Flight test data to validate the model;
• The AWARE simulation facility properly setup for the test.
• Authorities approval for this new methodology.
Objective was clear and challenging
• A first time for the Company and for civil helicopters.

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AWARE description- Hardwareand software
AWARE FEAURES:
• Immersive visual (5 channels, 160 deg x 65 deg)
• AW139 family static cockpit with accurate
emulation of real cockpit displays.
• Real-Time Monitoring specialist stations
• Physically consistent predictive models
(Flightlab© + Matlab© /Simulink© comprehensive
models)

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The Validation Campaign
A number of flights for practice and validation
• Experimental AW189 prototype P5.
• Entry into autorotation.
• Stabilized autorotation.
• Recovery initiations (with engine on).
Same flights have been simulated, checking
• Rotors speed.
• Pitch attitude at touch-down.
• Ground speed at touch-down.
• Vertical speed at touch-down.
And producing go ahead for the sim campaign
• Good quantitative matching.
• Higher workload, as seen in other cases, possibly due to
lower cues, producing conservative results

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The Simulation Campaign
A series of sim sessions performed to:
• Explore and define the manoeuvre technique in the
prescribed limits,proving feasibility and repeatability.
• Extend the manoeuvre to all required conditions (weight,
altitude).
• Demonstrate the EOL with EASA pilot in the AWARE
simulator.

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The Simulation Campaign
Outcomes and Lessons
• Demonstrated the AW189 to safely perform an EOL
up to the touchdown
• maneuvers judged acceptable;
• respecting prescribed constraints.
• Produced the relevant guidelines.
• The cues provided by the sim required some
compensation by the pilot and implied workload
higher than reality.
• Accepted by EASA (2013)
• Accepted by FAA (2014)

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Summary

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Supportto CATEGORY A Operationscertification
Definition from AIR-OPS regulation:
“Category A with respect to helicopters’means a multi-enginedhelicopter designed with engine
and system isolation features specifiedin the applicable airworthiness codes and capable of
operations using take-offand landing data scheduled under a critical engine failure
concept that assures adequate designatedsurfacearea and adequate performance
capability for continued safe flight or safe rejected take-off in the event of engine failure
respecting prescribed constraints.”
In summary, Cat. A means to have safe flight or safe landing after one engine failure.

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Example: Confined Area Heliport Engine Failure at or after TDP

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Current CAT. A evaluation & certification process:
• Lengthy and costly
• Requires long flight test campaigns in different geographical locations in order to assess:
• Procedures for different take-off andlanding surfaces (airport, helipad, off-shore)
• Ambient conditions (temperature and altitude)
• Risks involved:
• Proximity to the ground
• Low power settings
Possible benefits of certification by simulation approach
• Pilot in the loop simulation:
• Maneuver definition
• Offline simulation:
• “Filling” of test matrix to compute Flight Manual charts
• Actual flight testing reduced to verificationonly
• Much reduced time, cost and risk

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Supportto CATEGORY A Operationscertification:Engine modeltuning
Engine tuning in OEI conditions
• No dynamic engine model available from supplier → Tuning of a generic turboshaft engine model

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Supportto CATEGORY A Operationscertification:Physicalmodelvalidation
Example: Cat. A Offshore continued take-off
• Tens of flight test points replicated in simulation
• Very good matching found

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Supportto CATEGORY A Operationscertification:Prediction
Fly-Away from hover: Height loss prediction
• Confidence gained in simulation model thanks to validation
• Height loss from hover was predicted in order to give crew initial guess for flight testing
• Crew reported good matching between predictions and actual flight test results
Height
Loss
[ft]
Gross Weight [kg]
OAT

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Summary

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Additionalexamples of certificationby simulation and to supportto certification
2015 - AW139 7ton Power Off landing Certification by Simulation
Demonstration by simulationof the power off landing capability of the helicopter.
2015 - AW169 Power Off landing Certification by Simulation
Demonstration by simulationof the power off landing capability of the helicopter.
2016 – AW169 Demonstration of External Load Quick release
Demonstration by simulation, that the AW169 with cargo hook load is still controllable after quick release of
the load, with acceptable variation of the flight parameters and control inputs.
2017 – AW109S TREKKER power off certification by simulation
Demonstration by simulationof the power off landing capability of the helicopter
2017 – AW119 power off certification by simulation for 24000 ft extension
Simulationcampaignfor the extension of the Power off landing for high altitude conditionand support to
NEPAL campaign (24000 ft initiative). First FAR27 / single engine activity.
2010 - AW139 CATAprocedure rehearsal / familiarization for FAA
Risk reduction activity with Authorities in preparation for real tests and certification.
2014 - AW189 CATAoffshore supportto proceduredefinition
Preliminary exploration of the AW189 offshore CATAprocedure for risk reduction and preparationof the
experimental campaign
2017 - AW189 offshore CATAwith exposure and safe ditching simulations
Simulationcampaignsupportingnew CATAprocedure for the AW189, consideringdeck edge and water
surface constraints

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Summary

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Produce a consolidated set of guidelines, agreed with the
certification authority, and applicable to helicopters and
tiltrotors, to extend and facilitate standardized application
of flight simulation in the future certifications in Europe.
Main goal
What’s next?
The RoCS (Rotorcraft Certification by Simulation)project.

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In more detail, the research will try to answer these
questions:
Can any certificationparagraph be substitutedby simulation?
How good the simulationmodelneeds to be and in what respect?
How good the simulator cuing systems need to be?
Is the approach commonto all the certificationparagraphs?
What’s next?
The RoCS (Rotorcraft Certification by Simulation)project.

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This project has received funding from the Clean Sky 2
Joint Undertaking (JU) under grant agreement No
831969. The JU receives support from the European
Union’s Horizon 2020 research and innovation
programme and the Clean Sky 2 JU members other
than the Union

THANK YOU
FOR YOUR ATTENTION
leonardocompany.com
HELICO PTERS DIVISIO N

European Rotors - Certification by Simulation

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